Bearing for pneumatic servomotor



E. E. HUPP BEARING FOR PNEUMATIC SERVOMOTOR Original Filed Jan. 25, 1956 sept. 2o, 1966 United States Patent O 3,273,945 BEARING FOR PNEUMATIC SERVOMOTOR Edward E. Hupp, South Bend, Ind., assignor to The Bendix Corporation, South Bend, Ind., a corporation of Delaware Continuation of application Ser. No. 100,408, Apr. 3, 1961, which is a continuation of application Ser. No. 561,186, Jan. 25, 1956. This application Jan. 16, 1964, Ser. No. 338,064

1 Claim. (Cl. 308-4) This 'application is a continuation of my copending application Serial No. 100,408, filed April 3, 1961, now abandoned, as a continuation of a then copending application Serial No. 561,186, led January 25, 1956, covering a pneumatic servomotor, now abandoned.

The present invention relates to pneumatic powered servomotors of the type having control structures which must be guided for reciprocatory movement and which must be produced accurately and cheaply, and more particularly to inexpensive guide means for generally parallel surfaces which move longitudinally of each other.

An object of the invention is the provision of new and improved guide means lcomprising a piece of strip material bent to conform to the clearance between two generally parallel spaced surfaces which move longitudinally of each other, and positioned therebetween to act as a guide bearing for the surfaces.

Another object of the invention is the provision of new and improved guide means comprising a pair of pieces of strip material each bent to conform to the clearance between two generally parallel spaced surfaces, said pieces being positioned between the surfaces at spaced points to act as guide bearings for the surfaces.

Another object of the present invention is the provision of new and improved means for supporting and guiding a first member having a set of abutment surfaces spaced about its periphery, relative to a second member having a 'cooperating set of abutment surfaces positioned about the abutment surfaces of said rst member, and comprising a piece of strip material of predetermined thickness bent to conform to clearance provided -by said abutment surfaces when said sets of abutment surfaces are centered with respect to each other.

Another object of the invention is the provision of new and improved guide means of the above described type wherein the set of abutment surfaces on one of the members is shaped to conform to la portion of the surface of said strip material such that the piece of strip material is retained by the abutment surfaces during their reciprocatory movement.

Another object of the invention is the provision of new and improved guide means of the above described type in which the strip material is wire.

Another object of the invention is the provision of new and improved guide means for supporting and guiding the first member having longitudinally spaced first and second sets of abutment surfaces positioned about the member, relative to a second member having similarly longitudinally spaced first and second sets of cooperating abutment surfaces which respectively surround the first and second sets of abutment surfaces of said first member and comprising, a rst piece of strip material of predetermined thickness bent to conform to clearance provided by said rst sets of abutment surfaces when centered with respect to each other, and a second piece of strip material of predetermined thickness bent to conform to clearance provided by said second sets of abutment surfaces when centered with respect to each other.

An additional object of the invention is the provision of new and `improved guide means ofthe above described type in which one of the first sets of abutment surfaces Patented Sept. 20, 1906 and one of the second sets of abutment surfaces are shaped to conform to a portion of their respective pieces of strip material to retain said strips during reciprocatory movement of the surfaces.

An additional object of the invention is the provision of new and improved guide means of the `above described type in which said pieces of strip material are wire having a ring shape with spaced ends to form an opening therethrough.

A further object of the invention is the provision of new .and improved guide means for a first member having a cylindrically shaped surface concentrically positioned in a cylindrically shaped bore of a second member, said first member having a pair of longitudinally spaced grooves extending about its outer surface, and comprising a pair of pieces of wire of `a finite length and of predetermined thickness bent such that they can be received by said grooves, with a space between the ends of the wire one of said pieces of said wire being positioned in each groove to provide a pair of guide bearings which slidably engage the surface of `the second member.

A still further object of the invention is the provision of a new and improved servomotor having recipr-ocatory contol structure which must be moved with `a minimum of effort, said control structure employing members and guide structures `substantially as outlined in the above object to provide a servomotor which responds easily and accurately to manual control forces and which servomotor is inexpensive to manufacture.

The invention resides in `certain constructions and combinations .and arrangements of parts and further objects and advantages thereof will be apparent to those skilled in the art to which lthe invention relates from the following description of the preferred embodiment described with reference to the accompanying drawings forming a part of this specification, and in which:

FIGURE 1 is a longitudinal cross-sectional view of a servomotor embodying the principles of the present invention;

FIGURE 2 is an enlarged fragmentary sectional view of a portion of the guide structure of the servomotor shown in FIGURE l; and

FIGURE 3 is an enlarged view of `an important part of the guide structure shown in FIGURES l and 2.

Referring to the drawing there is shown therein a servomotor A of the type having `a movable wall provided with a force transmitting member of tubular projection 12 having an internal cylindrical bore 14 adapted to receive a cylindrically shaped valve closure member or rod adapted to actuate the valve structure of the servomotor. The inner end of the valve closure member 16 is provided with a vacuum poppet 18 adapted to abut an annular atmospheric valve member 20 to close od communication between the vacuum chamber 24 and the control chamber 26 of the valve s-tructure. For a complete description of the servomotor shown in the drawing reference may be had to the previously filed Edward E. Hupp application entitled Pneumatic Servo-Motor Construction Serial No. 559,556, now U.S. Patent No. 2,829,625.

In order that a general knowledge of the operation of the servomotor shown in the drawing can be had without referring to the above mentioned application, a short description of its operation will now be given. Suilce it to say that, inward movement of the valve control member 16 causes the vacuum poppet 18 positioned on its inner end to abut the annular atmospheric valve member 20 and thereafter force it off its atmospheric valve seat 22. Initial contact of the vacuum poppet 18 with the atmospheric valve member 20 closes off communication between the vacuum chamber 24 of the valve structure and the control chamber 26 of the valve structure. Continued inward movement of the poppet 18 causes the atmospheric valve member 20 to be lifted from the atmospheric valve seat 22 and thereby permit atmospheric pressure from the cylinder chamber 28 to be communicated with the control chamber 26 and in turn with cylinder chamber 30 through the passageway 36. since atmospheric pressure is normally supplied to the cylinder chamber 28 through the filtering material 32 and opening 34.

Opening of the atmospheric poppet, therefore, permits atmospherie pressure to enter chamber 30 thereby establishing the normally atmospheric submerged condition of the servomotor. By moving the vacuum poppet 18 outwardly or to the right as seen in FIGURE 1, atmospheric communication between the cylinder chambers 28 and 30 will be broken and upon separation of the vacuum poppet 18 from the atmospheric valve member 20, vacuum will be communicated to the cylinder chamber 30 thus energizing the servomotor to cause the movable wall 1t) to move rearwardly, or to the right as seen in the drawing. It will now be apparent that by suitably positioning the valve control member 16 with respect to the force transmitting member 12, control of the servomotor is obtained. It will further be apparent that suitable guide structure must be provided between the valve control member 16 and the force transmitting member 12 if the valve control structure is to operate smoothly and efficiently with a minimum of manual effort.

The guide structure shown in the drawing generally comprises a pair of longitudinally spaced pieces of strip material 40 and 42 which are bent to extend about the movable valve member 16 to provide a sliding fit with respect to the bore of the force transmitting member 12. Although numerous types of strip material may be utilized, wire is chosen for the preferred embodiment because it is cheap, is commercially made to close tolerances, can be obtained in numerous materials and sizes, can be bent easily, and provides a smooth rounded surface which slides readily with respect to other surfaces. Circumferentially extending grooves 44 and 46 are machined in the valve control member 16 to provide a seat for the ring shaped pieces of strip material 40 and 42. The grooves 44 and 46 correspond in shape to that of the wire used and are of a predetermined depth such that the depth of the groove plus the radial distance between the surface of the centered valve rod 16 and the walls of cylindrical bore 14 exceed the thickness of the wire to be used by an amount which would provide the desired running clearance between the strip material and the sides of the cylindrical bore 14. Use of wires made from spring materials, such as phosphorus bronze wire or piano wire, has been found to aid assembly of the parts, since such wires will return to their original shape after being expanded slightly. This permits them to tightly engage their seating groove after being slipped over member 16, to provide an outside diameter which will easily slip into the bore 14. A phosphorus bearing bronze wire has been found to be an excellent material for use with steel parts since it can be bent readily to the shape desired, it can be made to yieldably engage grooves 44 and 46 when positioned about control member 16, and since it is of a hardness suiliciently different from steel parts to be a good bearing material.

As is seen in the drawings, the wires 40 and 42 have been formed into a ring such that there is a space 48 between adjacent ends of the ring-shaped wires 40 and 42 shown by FIGURE 3. This permits communication of control chamber 26 with a forward chamber 50 so as to provide a balanced valve structure which requires a minimum of manual effort to operate. For more particular details on such valve structure and function attention is directed to my aforesaid Patent No,7 2,829,625,

While the guide structure of the present invention has been described as utilizing Wire and particularly phosbronze wire, it will be understood that the invention is not so limited and that wires of other than circular crosssection, and materials other than phos-bronze can be utilized, and further that strip materials other than wire may also be utilized where they are made of predetermined thickness and can be bent to the desired shape. It will also be understood that while the invention has been described as utilizing pieces of strip material between continuous concentrically positioned circular surfaces, it is not so limited, and that any arrangement wherein pieces of strip material, as for example wire, are used for guide bearing surfaces between members which slide relative to each other is contemplated by the present invention.

It will be apparent that the objects heretofore enumerated as well as others have been accomplished and that there has been provided a new and improved servomotor having new and improved guide bearing structure which is simple in design, rugged in construction and inexpensive to manufacture, and which guide structure can be adapted for use in other applications.

While the preferred embodiment of the invention has been shown and described in detail the invention is not limited to the particular construction shown and it is my intention to cover hereby all adaptations, modifications, and uses thereof which come within the practice of those skilled in the art to which the invention relates and within the scope of the appended claim.

I claim:

In guide structure and the like: a generally tubular member having a longitudinally extending chamber with longitudinally spaced apart surfaces of revolution, a rod in said chamber and also having longitudinally spaced apart surfaces of revolution, said surfaces of said rod having a diameter appreciably Vless than said surfaces of said tubular member and being positioned opposite to respective surfaces of said tubular member to form first and second sets of generally concentric surfaces with the respective surfaces of said tubular member, with a fluid passage- Way formed by the differing diameters of said chamber and rod surfaces, the surface of said rod being formed with longitudinally spaced grooves, first and second pieces of cold drawn wire positioned between said surfaces of respective sets, each of said wires having a diameter less than the clearance between the surfaces between which it is positioned by an amount providing a running reciprocatory t, each of said wires being bent into a torus shaped spring whose normal condition provides an interference lit with respect to its receiving groove, said torus shaped spring being snapped into said grooves to concentrically space and at two points contact said member and rod, one within the other, and said rod and member being reciprocable longitudinally of each other, whereby each piece of wire is retained in its groove and a clearance is maintained between the tips of said springs and the opposing surface such that said uid passageway is open from one end of said tubularmember to the other.

References Cited by the Examiner UNITED STATES PATENTS 1,061,603 5/1913 Foust.

2,049,265 7/1936 Kinney 308-4 2,517,180 8/1950 Davis 308-4 DAVID I. WILLIAMOWSKY, Primary Examiner.

F. SUSKO, Assistant Examiner. 

